| Dietary copper taken into the animal body will be distributed and accumulated in various tissues and organs,excessive copper in animal tissues and organs causes damage.However,the negative impact on human health after consuming these animal products is unknown.Therefore,this article seeks not only to investigate the performance of pig production,feed nutrient digestibility and copper metabolism,but also determine the exposure of copper risk assessment,and whether the ecological environment,meat and food safety problems has a great importance on the safety of pig breeding and production and processing.The main research methods were as follows: 24 healthy finishing pigs with weight,(30 ± 1.05)kg were randomly divided into four treatment groups,each with 3 replicates and 2 pigs per replicate.The contents of copper in the diet were 10 mg / kg(control group),45 mg / kg(group 1),135 mg / kg(group 2)and 225 mg / kg(group 3),respectively.(Control group),53.60 mg / kg(group 1),154.00 mg / kg(group 2)and 250 mg / kg(group 3)respectively.A total period of 87 days was used for the experiment.It was divided into two stages: the early stage was 30 ~ 60 kg,the late stage;60 ~ 100 kg.Pig manure was collected to determine the copper content on a weekly basis.The daily feed intake and weight gain were recorded.After 80 days of continuous feeding,pigs were slaughtered and their organs were removed to determine the copper content.1.Effect of Dietary Copper Levels on Growth Performance,Nutrient Digestibility and Copper Metabolism in Finishing PigsCompared with the control group,group 3 significantly reduced the weight of the finishing pigs,increased ADFI and significantly increased the F / G(P <0.05).Groups 1 and 2 were significantly reduced,the final weight of fattening pigs and ADG increased F / G(P> 0.05).Compared with the control group,the ADFI of groups 1,2 and 3 increased by 6.44%,8.19% and 13.30% respectively,and the ADG decreased by 7.89%,7.89% and 3.79% respectively,while the F / G increased by 8.80%,15.49% and 17.96% respectively.There was a significant difference in digestibility of NDF between the experimental groups and the control group(P <0.05),and the digestibility of crude protein and crude fat was significantly lower than that of the other three groups(P <0.05),but there was no significant difference between the experimental group and the control group(P> 0.05).Crude protein increased by 1.68%,2.83% and 5.76% and the crude fat increased by 45.85%,121.37% and 131.49% in groups 1,2 and 3 respectively.The ADF decreased by 2.44%?6.13%and7.80%and 34.43%,NDF decreased by 3.78%?3.78%and6.90%,respectively as compared with the control group(P <0.05).There was no significant difference between 53.60 mg / kg(group 1)and 154.00 mg / kg(group 2)(P> 0.05),and there was no significant difference between the other two groups(P> 0.05).There was a significant difference in copper apparent digestibility,copper deposition rate and total copper emission rate between the two groups(P> 0.05).Compared with the control group,the apparent digestibility of copper in test group 1,group 2 and group 3 was increased by 1.65%,2.58% and 5.78% respectively.The copper deposition rate increased by 14.22%,20.78% and 25.78%;Total copper emissions were increased by 14.46%,18.45% and 43.08% respectively.2.Effects of Dietary Copper on Copper Deposits in Tissues and OrgansThe pigs were slaughtered after 80 days of feeding,and the contents of copper were determined in the brain,heart,liver,kidney,spleen,lung,stomach,muscle tissue,bone,serum and pig hair.The results were as follows:(1)With the increase of copper content in the feed,the brain,liver,kidney and serum enrichment of copper was higher,followed by the tibia,ribs and bone marrow,and finally the muscle tissue.(2)Femoral bone,ribs and tibia,pig hair,liver,kidney and other tissues and organs had a higher copper content.(3)The content of copper in pig's hair,liver,kidney and bone tissue increased linearly with the increase of copper content in feed,thus the content of copper in feed was in accordance with national standard(?25mg / kg),but the copper content in these tissues and organs(0.054 mg / kg ~ 49.600 mg / kg)is still likely to exceed the standard(copper in the bone was not clearly defined).(4)The copper content in the heart,lung,stomach and muscle tissue was not significantly different from that in the feed.The copper content in the feed was more than 3 times higher than that of the national standard(copper content 250.00 mg / kg).Therefore,the copper content in tissues and organ is still lower than the national standard limit. |
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